Putting TCL mods for Python under CVS.

Mac/tclmods/license-terms.txt

+This software is copyrighted by the Regents of the University of
+California, Sun Microsystems, Inc., and other parties.  The following
+terms apply to all files associated with the software unless explicitly
+disclaimed in individual files.
+
+The authors hereby grant permission to use, copy, modify, distribute,
+and license this software and its documentation for any purpose, provided
+that existing copyright notices are retained in all copies and that this
+notice is included verbatim in any distributions. No written agreement,
+license, or royalty fee is required for any of the authorized uses.
+Modifications to this software may be copyrighted by their authors
+and need not follow the licensing terms described here, provided that
+the new terms are clearly indicated on the first page of each file where
+they apply.
+
+IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY
+FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ARISING OUT OF THE USE OF THIS SOFTWARE, ITS DOCUMENTATION, OR ANY
+DERIVATIVES THEREOF, EVEN IF THE AUTHORS HAVE BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+
+THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES,
+INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT.  THIS SOFTWARE
+IS PROVIDED ON AN "AS IS" BASIS, AND THE AUTHORS AND DISTRIBUTORS HAVE
+NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR
+MODIFICATIONS.
+
+GOVERNMENT USE: If you are acquiring this software on behalf of the
+U.S. government, the Government shall have only "Restricted Rights"
+in the software and related documentation as defined in the Federal 
+Acquisition Regulations (FARs) in Clause 52.227.19 (c) (2).  If you
+are acquiring the software on behalf of the Department of Defense, the
+software shall be classified as "Commercial Computer Software" and the
+Government shall have only "Restricted Rights" as defined in Clause
+252.227-7013 (c) (1) of DFARs.  Notwithstanding the foregoing, the
+authors grant the U.S. Government and others acting in its behalf
+permission to use and distribute the software in accordance with the
+terms specified in this license. 

Mac/tclmods/tclMacNotify.c

+/* 
+ * tclMacNotify.c --
+ *
+ *	This file contains Macintosh-specific procedures for the notifier,
+ *	which is the lowest-level part of the Tcl event loop.  This file
+ *	works together with ../generic/tclNotify.c.
+ *
+ * Copyright (c) 1995-1996 Sun Microsystems, Inc.
+ *
+ * See the file "license.terms" for information on usage and redistribution
+ * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+ *
+ * SCCS: @(#) tclMacNotify.c 1.36 97/05/07 19:09:29
+ */
+
+#include "tclInt.h"
+#include "tclPort.h"
+#include "tclMac.h"
+#include "tclMacInt.h"
+#include <signal.h>
+#include <Events.h>
+#include <LowMem.h>
+#include <Processes.h>
+#include <Timer.h>
+
+
+/* 
+ * This is necessary to work around a bug in Apple's Universal header files
+ * for the CFM68K libraries.
+ */
+
+#ifdef __CFM68K__
+#undef GetEventQueue
+extern pascal QHdrPtr GetEventQueue(void)
+ THREEWORDINLINE(0x2EBC, 0x0000, 0x014A);
+#pragma import list GetEventQueue
+#define GetEvQHdr() GetEventQueue()
+#endif
+
+/*
+ * The follwing static indicates whether this module has been initialized.
+ */
+
+static int initialized = 0;
+
+/*
+ * The following structure contains the state information for the
+ * notifier module.
+ */
+
+static struct {
+    int timerActive;		/* 1 if timer is running. */
+    Tcl_Time timer;		/* Time when next timer event is expected. */
+    int flags;			/* OR'ed set of flags defined below. */
+    Point lastMousePosition;	/* Last known mouse location. */
+    RgnHandle utilityRgn;	/* Region used as the mouse region for
+				 * WaitNextEvent and the update region when
+				 * checking for events. */   
+    Tcl_MacConvertEventPtr eventProcPtr;
+				/* This pointer holds the address of the
+				 * function that will handle all incoming
+				 * Macintosh events. */
+} notifier;
+
+/*
+ * The following defines are used in the flags field of the notifier struct.
+ */
+
+#define NOTIFY_IDLE	(1<<1)	/* Tcl_ServiceIdle should be called. */
+#define NOTIFY_TIMER	(1<<2)	/* Tcl_ServiceTimer should be called. */
+
+/*
+ * Prototypes for procedures that are referenced only in this file:
+ */
+
+static int		HandleMacEvents _ANSI_ARGS_((void));
+static void		InitNotifier _ANSI_ARGS_((void));
+static void		NotifierExitHandler _ANSI_ARGS_((
+			    ClientData clientData));
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * InitNotifier --
+ *
+ *	Initializes the notifier structure.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Creates a new exit handler.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+InitNotifier(void)
+{
+    initialized = 1;
+    memset(&notifier, 0, sizeof(notifier));
+    Tcl_CreateExitHandler(NotifierExitHandler, NULL);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * NotifierExitHandler --
+ *
+ *	This function is called to cleanup the notifier state before
+ *	Tcl is unloaded.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+NotifierExitHandler(
+    ClientData clientData)	/* Not used. */
+{
+    initialized = 0;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * HandleMacEvents --
+ *
+ *	This function checks for events from the Macintosh event queue.
+ *
+ * Results:
+ *	Returns 1 if event found, 0 otherwise.
+ *
+ * Side effects:
+ *	Pulls events off of the Mac event queue and then calls
+ *	convertEventProc.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+HandleMacEvents(void)
+{
+    EventRecord theEvent;
+    int eventFound = 0, needsUpdate = 0;
+    Point currentMouse;
+    WindowRef windowRef;
+    Rect mouseRect;
+
+    /*
+     * Check for mouse moved events.  These events aren't placed on the
+     * system event queue unless we call WaitNextEvent.
+     */
+
+    GetGlobalMouse(&currentMouse);
+    if ((notifier.eventProcPtr != NULL) &&
+	    !EqualPt(currentMouse, notifier.lastMousePosition)) {
+	notifier.lastMousePosition = currentMouse;
+	theEvent.what = nullEvent;
+	if ((*notifier.eventProcPtr)(&theEvent) == true) {
+	    eventFound = 1;
+	}
+    }
+
+    /*
+     * Check for update events.  Since update events aren't generated
+     * until we call GetNextEvent, we may need to force a call to
+     * GetNextEvent, even if the queue is empty.
+     */
+
+    for (windowRef = FrontWindow(); windowRef != NULL;
+	    windowRef = GetNextWindow(windowRef)) {
+	GetWindowUpdateRgn(windowRef, notifier.utilityRgn);
+	if (!EmptyRgn(notifier.utilityRgn)) {
+	    needsUpdate = 1;
+	    break;
+	}
+    }
+    
+    /*
+     * Process events from the OS event queue.
+     */
+
+    while (needsUpdate || (GetEvQHdr()->qHead != NULL)) {
+	GetGlobalMouse(&currentMouse);
+	SetRect(&mouseRect, currentMouse.h, currentMouse.v,
+		currentMouse.h + 1, currentMouse.v + 1);
+	RectRgn(notifier.utilityRgn, &mouseRect);
+	
+	WaitNextEvent(everyEvent, &theEvent, 5, notifier.utilityRgn);
+	needsUpdate = 0;
+	if ((notifier.eventProcPtr != NULL)
+		&& ((*notifier.eventProcPtr)(&theEvent) == true)) {
+	    eventFound = 1;
+	}
+    }
+    
+    return eventFound;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_SetTimer --
+ *
+ *	This procedure sets the current notifier timer value.  The
+ *	notifier will ensure that Tcl_ServiceAll() is called after
+ *	the specified interval, even if no events have occurred.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Replaces any previous timer.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tcl_SetTimer(
+    Tcl_Time *timePtr)		/* New value for interval timer. */
+{
+    if (!timePtr) {
+	notifier.timerActive = 0;
+    } else {
+	/*
+	 * Compute when the timer should fire.
+	 */
+	
+	TclpGetTime(&notifier.timer);
+	notifier.timer.sec += timePtr->sec;
+	notifier.timer.usec += timePtr->usec;
+	if (notifier.timer.usec >= 1000000) {
+	    notifier.timer.usec -= 1000000;
+	    notifier.timer.sec += 1;
+	}
+	notifier.timerActive = 1;
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_WaitForEvent --
+ *
+ *	This function is called by Tcl_DoOneEvent to wait for new
+ *	events on the message queue.  If the block time is 0, then
+ *	Tcl_WaitForEvent just polls the event queue without blocking.
+ *
+ * Results:
+ *	Always returns 0.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_WaitForEvent(
+    Tcl_Time *timePtr)		/* Maximum block time. */
+{
+    int found;
+    EventRecord macEvent;
+    long sleepTime = 5;
+    long ms;
+    Point currentMouse;
+    void * timerToken;
+    Rect mouseRect;
+
+    /*
+     * Compute the next timeout value.
+     */
+
+    if (!timePtr) {
+	ms = INT_MAX;
+    } else {
+	ms = (timePtr->sec * 1000) + (timePtr->usec / 1000);
+    }
+    timerToken = TclMacStartTimer((long) ms);
+   
+    /*
+     * Poll the Mac event sources.  This loop repeats until something
+     * happens: a timeout, a socket event, mouse motion, or some other
+     * window event.  Note that we don't call WaitNextEvent if another
+     * event is found to avoid context switches.  This effectively gives
+     * events coming in via WaitNextEvent a slightly lower priority.
+     */
+
+    found = 0;
+    if (notifier.utilityRgn == NULL) {
+	notifier.utilityRgn = NewRgn();
+    }
+
+    while (!found) {
+	/*
+	 * Check for generated and queued events.
+	 */
+
+	if (HandleMacEvents()) {
+	    found = 1;
+	}
+
+	/*
+	 * Check for time out.
+	 */
+
+	if (!found && TclMacTimerExpired(timerToken)) {
+	    found = 1;
+	}
+	
+	/*
+	 * Mod by Jack: poll for select() events. Code is in TclSelectNotify.c
+	 */
+	{
+	    int Tcl_PollSelectEvent(void);
+	    if (!found && Tcl_PollSelectEvent())
+		found = 1;
+	}
+
+	/*
+	 * Check for window events.  We may receive a NULL event for
+	 * various reasons. 1) the timer has expired, 2) a mouse moved
+	 * event is occuring or 3) the os is giving us time for idle
+	 * events.  Note that we aren't sharing the processor very
+	 * well here.  We really ought to do a better job of calling
+	 * WaitNextEvent for time slicing purposes.
+	 */
+
+	if (!found) {
+	    /*
+	     * Set up mouse region so we will wake if the mouse is moved.
+	     * We do this by defining the smallest possible region around
+	     * the current mouse position.
+	     */
+
+	    GetGlobalMouse(&currentMouse);
+	    SetRect(&mouseRect, currentMouse.h, currentMouse.v,
+		    currentMouse.h + 1, currentMouse.v + 1);
+	    RectRgn(notifier.utilityRgn, &mouseRect);
+	
+	    WaitNextEvent(everyEvent, &macEvent, sleepTime,
+		    notifier.utilityRgn);
+
+	    if (notifier.eventProcPtr != NULL) {
+		if ((*notifier.eventProcPtr)(&macEvent) == true) {
+		    found = 1;
+		}
+	    }
+	}
+    }
+    TclMacRemoveTimer(timerToken);
+    return 0;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_Sleep --
+ *
+ *	Delay execution for the specified number of milliseconds.  This
+ *	is not a very good call to make.  It will block the system -
+ *	you will not even be able to switch applications.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Time passes.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tcl_Sleep(
+    int ms)			/* Number of milliseconds to sleep. */
+{
+    EventRecord dummy;
+    void *timerToken;
+    
+    if (ms <= 0) {
+	return;
+    }
+    
+    timerToken = TclMacStartTimer((long) ms);
+    while (1) {
+	WaitNextEvent(0, &dummy, (ms / 16.66) + 1, NULL);
+	
+	if (TclMacTimerExpired(timerToken)) {
+	    break;
+	}
+    }
+    TclMacRemoveTimer(timerToken);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_MacSetEventProc --
+ *
+ *	This function sets the event handling procedure for the 
+ *	application.  This function will be passed all incoming Mac
+ *	events.  This function usually controls the console or some
+ *	other entity like Tk.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Changes the event handling function.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tcl_MacSetEventProc(
+    Tcl_MacConvertEventPtr procPtr)
+{
+    notifier.eventProcPtr = procPtr;
+}

Mac/tclmods/tclSelectNotify.c

+/*
+ * tclSelectNotify.c --
+ *
+ * Partial even handling, select only. This file is adapted from TclUnixNotify.c, and
+ * meant as an add-in for Mac (and possibly Windows) environments where select *is* available.
+ * TclMacNotify.c works together with this file.
+ *
+ * Copyright (c) 1995-1997 Sun Microsystems, Inc.
+ *
+ * See the file "license.terms" for information on usage and redistribution
+ * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+ *
+ * SCCS: @(#) tclUnixNotfy.c 1.42 97/07/02 20:55:44
+ */
+
+#if defined(__CFM68K__) && !defined(__USING_STATIC_LIBS__)
+	#pragma import on
+#endif
+
+#include <unistd.h>
+
+#if defined(__CFM68K__) && !defined(__USING_STATIC_LIBS__)
+	#pragma import reset
+#endif
+
+#include "tclInt.h"
+#include "tclPort.h"
+#include <signal.h> 
+
+#ifndef MASK_SIZE
+#define MASK_SIZE howmany(FD_SETSIZE, NFDBITS)
+#endif
+#ifndef SELECT_MASK
+#define SELECT_MASK fd_set
+#endif
+
+/* Prototype (too lazy to create new .h) */
+int Tcl_PollSelectEvent(void);
+
+/*
+ * This structure is used to keep track of the notifier info for a 
+ * a registered file.
+ */
+
+typedef struct FileHandler {
+    int fd;
+    int mask;			/* Mask of desired events: TCL_READABLE,
+				 * etc. */
+    int readyMask;		/* Mask of events that have been seen since the
+				 * last time file handlers were invoked for
+				 * this file. */
+    Tcl_FileProc *proc;		/* Procedure to call, in the style of
+				 * Tcl_CreateFileHandler. */
+    ClientData clientData;	/* Argument to pass to proc. */
+    struct FileHandler *nextPtr;/* Next in list of all files we care about. */
+} FileHandler;
+
+/*
+ * The following structure is what is added to the Tcl event queue when
+ * file handlers are ready to fire.
+ */
+
+typedef struct FileHandlerEvent {
+    Tcl_Event header;		/* Information that is standard for
+				 * all events. */
+    int fd;			/* File descriptor that is ready.  Used
+				 * to find the FileHandler structure for
+				 * the file (can't point directly to the
+				 * FileHandler structure because it could
+				 * go away while the event is queued). */
+} FileHandlerEvent;
+
+/*
+ * The following static structure contains the state information for the
+ * select based implementation of the Tcl notifier.
+ */
+
+static struct {
+    FileHandler *firstFileHandlerPtr;
+				/* Pointer to head of file handler list. */
+    fd_mask checkMasks[3*MASK_SIZE];
+				/* This array is used to build up the masks
+				 * to be used in the next call to select.
+				 * Bits are set in response to calls to
+				 * Tcl_CreateFileHandler. */
+    fd_mask readyMasks[3*MASK_SIZE];
+				/* This array reflects the readable/writable
+				 * conditions that were found to exist by the
+				 * last call to select. */
+    int numFdBits;		/* Number of valid bits in checkMasks
+				 * (one more than highest fd for which
+				 * Tcl_WatchFile has been called). */
+} notifier;
+
+/*
+ * The following static indicates whether this module has been initialized.
+ */
+
+static int initialized = 0;
+
+/*
+ * Static routines defined in this file.
+ */
+
+static void		InitNotifier _ANSI_ARGS_((void));
+static void		NotifierExitHandler _ANSI_ARGS_((
+			    ClientData clientData));
+static int		FileHandlerEventProc _ANSI_ARGS_((Tcl_Event *evPtr,
+			    int flags));
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * InitNotifier --
+ *
+ *	Initializes the notifier state.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Creates a new exit handler.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+InitNotifier()
+{
+    initialized = 1;
+    memset(&notifier, 0, sizeof(notifier));
+    Tcl_CreateExitHandler(NotifierExitHandler, NULL);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * NotifierExitHandler --
+ *
+ *	This function is called to cleanup the notifier state before
+ *	Tcl is unloaded.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Destroys the notifier window.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+NotifierExitHandler(clientData)
+    ClientData clientData;		/* Not used. */
+{
+    initialized = 0;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_CreateFileHandler --
+ *
+ *	This procedure registers a file handler with the Xt notifier.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Creates a new file handler structure and registers one or more
+ *	input procedures with Xt.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tcl_CreateFileHandler(fd, mask, proc, clientData)
+    int fd;			/* Handle of stream to watch. */
+    int mask;			/* OR'ed combination of TCL_READABLE,
+				 * TCL_WRITABLE, and TCL_EXCEPTION:
+				 * indicates conditions under which
+				 * proc should be called. */
+    Tcl_FileProc *proc;		/* Procedure to call for each
+				 * selected event. */
+    ClientData clientData;	/* Arbitrary data to pass to proc. */
+{
+    FileHandler *filePtr;
+    int index, bit;
+    
+    if (!initialized) {
+	InitNotifier();
+    }
+
+    for (filePtr = notifier.firstFileHandlerPtr; filePtr != NULL;
+	    filePtr = filePtr->nextPtr) {
+	if (filePtr->fd == fd) {
+	    break;
+	}
+    }
+    if (filePtr == NULL) {
+	filePtr = (FileHandler*) ckalloc(sizeof(FileHandler)); /* MLK */
+	filePtr->fd = fd;
+	filePtr->readyMask = 0;
+	filePtr->nextPtr = notifier.firstFileHandlerPtr;
+	notifier.firstFileHandlerPtr = filePtr;
+    }
+    filePtr->proc = proc;
+    filePtr->clientData = clientData;
+    filePtr->mask = mask;
+
+    /*
+     * Update the check masks for this file.
+     */
+
+    index = fd/(NBBY*sizeof(fd_mask));
+    bit = 1 << (fd%(NBBY*sizeof(fd_mask)));
+    if (mask & TCL_READABLE) {
+	notifier.checkMasks[index] |= bit;
+    } else {
+	notifier.checkMasks[index] &= ~bit;
+    } 
+    if (mask & TCL_WRITABLE) {
+	(notifier.checkMasks+MASK_SIZE)[index] |= bit;
+    } else {
+	(notifier.checkMasks+MASK_SIZE)[index] &= ~bit;
+    }
+    if (mask & TCL_EXCEPTION) {
+	(notifier.checkMasks+2*(MASK_SIZE))[index] |= bit;
+    } else {
+	(notifier.checkMasks+2*(MASK_SIZE))[index] &= ~bit;
+    }
+    if (notifier.numFdBits <= fd) {
+	notifier.numFdBits = fd+1;
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_DeleteFileHandler --
+ *
+ *	Cancel a previously-arranged callback arrangement for
+ *	a file.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	If a callback was previously registered on file, remove it.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tcl_DeleteFileHandler(fd)
+    int fd;		/* Stream id for which to remove callback procedure. */
+{
+    FileHandler *filePtr, *prevPtr;
+    int index, bit, mask, i;
+
+    if (!initialized) {
+	InitNotifier();
+    }
+
+    /*
+     * Find the entry for the given file (and return if there
+     * isn't one).
+     */
+
+    for (prevPtr = NULL, filePtr = notifier.firstFileHandlerPtr; ;
+	    prevPtr = filePtr, filePtr = filePtr->nextPtr) {
+	if (filePtr == NULL) {
+	    return;
+	}
+	if (filePtr->fd == fd) {
+	    break;
+	}
+    }
+
+    /*
+     * Update the check masks for this file.
+     */
+
+    index = fd/(NBBY*sizeof(fd_mask));
+    bit = 1 << (fd%(NBBY*sizeof(fd_mask)));
+
+    if (filePtr->mask & TCL_READABLE) {
+	notifier.checkMasks[index] &= ~bit;
+    }
+    if (filePtr->mask & TCL_WRITABLE) {
+	(notifier.checkMasks+MASK_SIZE)[index] &= ~bit;
+    }
+    if (filePtr->mask & TCL_EXCEPTION) {
+	(notifier.checkMasks+2*(MASK_SIZE))[index] &= ~bit;
+    }
+
+    /*
+     * Find current max fd.
+     */
+
+    if (fd+1 == notifier.numFdBits) {
+	for (notifier.numFdBits = 0; index >= 0; index--) {
+	    mask = notifier.checkMasks[index]
+		| (notifier.checkMasks+MASK_SIZE)[index]
+		| (notifier.checkMasks+2*(MASK_SIZE))[index];
+	    if (mask) {
+		for (i = (NBBY*sizeof(fd_mask)); i > 0; i--) {
+		    if (mask & (1 << (i-1))) {
+			break;
+		    }
+		}
+		notifier.numFdBits = index * (NBBY*sizeof(fd_mask)) + i;
+		break;
+	    }
+	}
+    }
+
+    /*
+     * Clean up information in the callback record.
+     */
+
+    if (prevPtr == NULL) {
+	notifier.firstFileHandlerPtr = filePtr->nextPtr;
+    } else {
+	prevPtr->nextPtr = filePtr->nextPtr;
+    }
+    ckfree((char *) filePtr);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * FileHandlerEventProc --
+ *
+ *	This procedure is called by Tcl_ServiceEvent when a file event
+ *	reaches the front of the event queue.  This procedure is
+ *	responsible for actually handling the event by invoking the
+ *	callback for the file handler.
+ *
+ * Results:
+ *	Returns 1 if the event was handled, meaning it should be removed
+ *	from the queue.  Returns 0 if the event was not handled, meaning
+ *	it should stay on the queue.  The only time the event isn't
+ *	handled is if the TCL_FILE_EVENTS flag bit isn't set.
+ *
+ * Side effects:
+ *	Whatever the file handler's callback procedure does.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+FileHandlerEventProc(evPtr, flags)
+    Tcl_Event *evPtr;		/* Event to service. */
+    int flags;			/* Flags that indicate what events to
+				 * handle, such as TCL_FILE_EVENTS. */
+{
+    FileHandler *filePtr;
+    FileHandlerEvent *fileEvPtr = (FileHandlerEvent *) evPtr;
+    int mask;
+
+    if (!(flags & TCL_FILE_EVENTS)) {
+	return 0;
+    }
+
+    /*
+     * Search through the file handlers to find the one whose handle matches
+     * the event.  We do this rather than keeping a pointer to the file
+     * handler directly in the event, so that the handler can be deleted
+     * while the event is queued without leaving a dangling pointer.
+     */
+
+    for (filePtr = notifier.firstFileHandlerPtr; filePtr != NULL;
+	    filePtr = filePtr->nextPtr) {
+	if (filePtr->fd != fileEvPtr->fd) {
+	    continue;
+	}
+
+	/*
+	 * The code is tricky for two reasons:
+	 * 1. The file handler's desired events could have changed
+	 *    since the time when the event was queued, so AND the
+	 *    ready mask with the desired mask.
+	 * 2. The file could have been closed and re-opened since
+	 *    the time when the event was queued.  This is why the
+	 *    ready mask is stored in the file handler rather than
+	 *    the queued event:  it will be zeroed when a new
+	 *    file handler is created for the newly opened file.
+	 */
+
+	mask = filePtr->readyMask & filePtr->mask;
+	filePtr->readyMask = 0;
+	if (mask != 0) {
+	    (*filePtr->proc)(filePtr->clientData, mask);
+	}
+	break;
+    }
+    return 1;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_PollSelectEvent --
+ *
+ *	This function is called by Tcl_WaitForEvent to wait for new
+ *	events on the message queue.  If the block time is 0, then
+ *	Tcl_WaitForEvent just polls without blocking.
+ *
+ * Results:
+ *	Returns 1 if any event handled, 0 otherwise.
+ *
+ * Side effects:
+ *	Queues file events that are detected by the select.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_PollSelectEvent(void)
+{
+    FileHandler *filePtr;
+    FileHandlerEvent *fileEvPtr;
+    struct timeval timeout, *timeoutPtr;
+    int bit, index, mask, numFound;
+
+    if (!initialized) {
+	InitNotifier();
+    }
+
+    /*
+     * Set up the timeout structure. 
+     */
+
+    timeout.tv_sec = 0;
+    timeout.tv_usec = 0;
+    timeoutPtr = &timeout;
+
+    memcpy((VOID *) notifier.readyMasks, (VOID *) notifier.checkMasks,
+	    3*MASK_SIZE*sizeof(fd_mask));
+    numFound = select(notifier.numFdBits,
+	    (SELECT_MASK *) &notifier.readyMasks[0],
+	    (SELECT_MASK *) &notifier.readyMasks[MASK_SIZE],
+	    (SELECT_MASK *) &notifier.readyMasks[2*MASK_SIZE], timeoutPtr);
+
+    /*
+     * Some systems don't clear the masks after an error, so
+     * we have to do it here.
+     */
+
+    if (numFound == -1) {
+	memset((VOID *) notifier.readyMasks, 0, 3*MASK_SIZE*sizeof(fd_mask));
+    }
+    
+    /*
+     * Return if nothing to do.
+     */
+    if ( numFound == 0 )
+    	return 0;
+
+    /*
+     * Queue all detected file events before returning.
+     */
+
+    for (filePtr = notifier.firstFileHandlerPtr;
+	    (filePtr != NULL) && (numFound > 0);
+	    filePtr = filePtr->nextPtr) {
+	index = filePtr->fd / (NBBY*sizeof(fd_mask));
+	bit = 1 << (filePtr->fd % (NBBY*sizeof(fd_mask)));
+	mask = 0;
+
+	if (notifier.readyMasks[index] & bit) {
+	    mask |= TCL_READABLE;
+	}
+	if ((notifier.readyMasks+MASK_SIZE)[index] & bit) {
+	    mask |= TCL_WRITABLE;
+	}
+	if ((notifier.readyMasks+2*(MASK_SIZE))[index] & bit) {
+	    mask |= TCL_EXCEPTION;
+	}
+
+	if (!mask) {
+	    continue;
+	} else {
+	    numFound--;
+	}
+
+	/*
+	 * Don't bother to queue an event if the mask was previously
+	 * non-zero since an event must still be on the queue.
+	 */
+
+	if (filePtr->readyMask == 0) {
+	    fileEvPtr = (FileHandlerEvent *) ckalloc(
+		sizeof(FileHandlerEvent));
+	    fileEvPtr->header.proc = FileHandlerEventProc;
+	    fileEvPtr->fd = filePtr->fd;
+	    Tcl_QueueEvent((Tcl_Event *) fileEvPtr, TCL_QUEUE_TAIL);
+	}
+	filePtr->readyMask = mask;
+    }
+    return 1;
+}